hard to believe

[redriverhunter]

I know this is cast boolit but, I feel that what the results of these two bullets needed to be shared. I would have never thought. In the target on the right was a 2 shot group with a .308 win. 180 gn sst propelled by 44.5gns of Varget. The target on the left was shot with .308 win (same rifle) 165 gn Hornady interlock flat base propelled by 45.5 gns of Varget. The targets were at 100 yards. I did not have my tape measure so i used a sheet of paper which is 8.5X11. The load data came from Hodgdons' web page and both are .5 under max charge. I would have never thought that I would have an 11 inch drop and why 8.5 + inches to the right. This reinforces always shoot a target to be certain how your ammo will preform.

[Der Gebirgsjager]

Hmmm...it is interesting. Kind of goes with the idea though that faster (165 gr./45.5 gr. Varget vs. (slower) 180 gr./44.5 gr. Varget is lower. No ready explanation for the group to the right, except that different charges do result in movement of groups to right or left. Could be that the barrel's rifling rate of twist is more suited to one bullet weight than the other. You're certainly right about verifying your loads on paper. That might be enough to miss a game animal or score a poorly placed hit.

[Norske]

If you rested your rifle on sand bags (or worse a lead sled), it could have bounced from recoil that much. If you had your front hand between the sand bag and fore end, that's strange.

[crackers]

Naw. There's something there that's actually rattling.

[Texas by God]

What rifle? Crackers has a point- check all the screws. That's a big difference, but the groups are good. Try a different scope if the present one won't pass the box test.

Sent from my SAMSUNG-SM-G930A using Tapatalk

[Mrlucky353]

If you rested your rifle on sand bags (or worse a lead sled), it could have bounced from recoil that much. If you had your front hand between the sand bag and fore end, that's strange.

What should I use as a better alternative for a rifle rest?

[Murphy]

I had a similar experience back in the 90's. The rifle, was a Springfield Armory M1A. I had shot military surplus loads, standard ball to sight it in. I shot it a few times and all was well. I decided to work up a hunting load for deer season, it was the only rifle I had at the time. I decided to give both 150 grain and 165 grain bullets a try. I wish I had kept records back then for it. I sand bagged the gun and touched off a shot. Whoa! That can't be right. The next four rounds proved me wrong. I never looked for the cause of what caused such a vastly different point of impact. I did however, find an excellent 165 Grain load and do have the data for it.

Change any part of the equation of a handload, and you can expect some change. I'd just never seen one so drastic. That being said, without fail, I target a gun before carrying it afield.

Murphy

[samari46]

Have a Sako 75 hunter in 30-06. Handload chronographs 2800 fps. 165 Nosler ballistic tip, Fed case, 55.5 grs IMR 4350 CCI magnum primer. Rifle is sighted in for that load. Lake City 63 match 173 grain bullet @ 2640 fps. Shoots within 1" of my handload. Go figure!. Frank

[Norske]

The best rifle rest I've found (if matching what the rifle will do when handheld is important) is a rolled up sleeping bag. The fore end sinks, so not much side-to-side movement, and zero recoil bounce. Remember, even with those heavy WW1 bolt action rifles, the gun had moved 1/2" before the bullet left the muzzle.
Your experience is very similar to what one of my 30-06 rifles did when I compared 180 Hornady round nose bullets to their 178 gr ELD hunting bullets.

[Win94ae]

Yes there can be all sorts of things that explain the POI oddity, sand bags isn't one.

[tazman]

I have tested loads in several rifles and had the impact point move a large distance away from point of aim simply by changing the bullet weight.
I had a 243 that grouped very well at 100 with 90 grain bullets and tried a 55 grain bullet. That one printed 8 inches straight left at 100 yards. Beautiful group though.
Other rifles have done similar things. The oddest rifle I have shoots every bullet weight I have tried into the same 1.5 inch group at 100 yards.
'The only time I need to change the scope is to adjust for distance. I am keeping this one for hunting.

[Texas by God]

In my experience, it's a rare rifle that shoots all bullet weights together- but Tazman has one and so does my wife. Her .250 Savage bolt action will shoot 75 to 120 grain bullets into a 2" group. I've done it a few times.
She insists that I leave it alone with some 87 gr Speer bullets at 3000 fps handy.
My 22-250 freaks out on a 20gr difference in bullets and 600 fps in velocity.......

Sent from my SM-A716U using Tapatalk

[725]

Not knowing many of the particulars, I'd hazard a guess that the two different bullet weights have induced different barrel harmonics and the result is a different POI.

[atr]

I've had some pretty radical changes to point of impact also so I am not surprised at your results

[M-Tecs]

Not knowing many of the particulars, I'd hazard a guess that the two different bullet weights have induced different barrel harmonics and the result is a different POI.

That would be my guess also. Changes in POI with different loads and or bullet weights have been the norm for me. I have personally not experienced any that much but I have had as much as 6" POI change at a 100 with as simple ammunition brand change when shooting factory 30/06 of the same weight. I also have some guns that are effected very little by this. Until you test you never know.

[Goofy]

Barrel harmonics variation would be my guess. Groups are suitable for hunting regardless.

[Geezer in NH]

Count two shot group? No repeat it 20 times maybe

[Earlwb]

I have seen it change from lot to lot with ammunition too. The competition guys get all they can from one lot of ammo made as the point of impact can change from different lots of ammo made. You can have the same problem when you buy one box of ammo one year and then a year later buy another box just like the last, but the point of impact can be different. The factory can change propellant or brass cases or bullets or primers even. it is enough to affect the performance.

[robg]

im more consistent if i hold the fore end of my rifles with my hand on the bag/rest. especially leverguns .